1. Field
This invention relates to intravenous fluid therapy systems. More particularly, this invention provides an intravenous fluid therapy system to provide intravenous fluid under pressure without exposure or contact of the intravenous fluid to the atmosphere.
2. State of the Art
Intravenous (IV) therapy systems are well known. In general, they include a fluid supply and a catheter apparatus within interconnecting tubing. A metering device such as a drip chamber may be provided in the interconnecting tubing to permit adjustment of the intravenous fluid flow rate and in turn the injection rate into the vein (or vessel) of a patient. In particular, a catheter apparatus which is frequently of the type comprised of a stylet in a cannula attached to a hub is inserted into a patient's vein (or vessel). After insertion, the stylet is removed and intravenous system tubing is connected to the hub. The tubing is in turn connected to a fluid supply which may be a bottle or bag of intravenous fluid suspended at a height above the intravenous therapy site so that a fluid head in excess of blood pressure is available to cause fluid flow. The source of IV fluid is frequently vented to the atmosphere. The atmosphere generally contains a wide variety of microscopic or otherwise small particulate matter which may in many circumstances be detrimental if injected into a patient's blood stream. By venting an IV fluid system to the atmosphere, there exists a distinct possibility that undesirable organisms or matter may become suspended or dissolved in the intravenous fluid and thereby be injected into the blood system of a patient. Further, a drip chamber is typically vented so that fluid literally drips through a chamber vented to the atmosphere. The drip rate (number of drops per unit time) is frequently used as an indicia of IV therapy flow rate and administration rate (milliliters per unit time). Accordingly, IV fluid may be exposed to the atmosphere both through the source (bottle) which may be vented to the atmosphere and through a drip chamber. Also, some spillage has occurred with the use of vented bottles.
In a hospital, frequently the atmosphere can be more hazardous than ordinary atmosphere. That is, in selected circumstances, one may find a variety of contagious organisms or hazardous matter. Because of the increased and wide use of antibiotics in medical treatment, and in particular in hospitals, it is generally known that a variety of antibiotic-resistant organisms may become airborne to expose patients to what has been termed "staph" infection or similar maladies. A vented inrtraveous therapy system is particularly susceptible to becoming a vehicle which communicates these airborne organisms into a patient.
In any vented intravenous fluid system, it is distinctly possible that air may be entrained in the tubing and thereafter injected into the patient. Injection of air into a blood vessel can have fatal consequences.
Also, IV therapy in environments where atmospheric pressure is varying or abnormal or where gravity is not reliable (e.g., airborne, space, decompression chamber) is difficult because of problems in flow rate and the risks of dissolved gases going into or coming out of solution. A sealed or airless system is desirable for such applications.